"Melting and Solidification" Changes in State of Matter PPT Courseware 7

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"Melting and Solidification" Changes in State of Matter PPT Courseware 7

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1. Melting - the process by which a substance changes from solid to liquid.

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2. Solidification - the process of matter changing from liquid to solid.

Explore the temperature changes when solids melt

Ask a question: Do the temperature changes of different substances during the melting process from solid to liquid are the same?

Conjecture hypothesis: The melting process must be heated, so the material must absorb heat. The temperature may also be rising at this time.

conduct experiment:

(1) Four students form a group, and each group is divided into two groups.

(2) Understand the experimental device, as shown in the figure, emphasizing the use of alcohol lamps and thermometers.

(3) Group 1 explores the temperature changes when naphthalene melts.

The second team explored the temperature changes when paraffin melted.

Crystal melting characteristics:

Heat continues to be absorbed and the temperature remains constant.

Understand the crystal melting curve:

(1) The material in segment AB is in a solid state, indicating the process of crystal endothermic heating.

(2) The material in the BC segment is in a solid-liquid coexistence state, indicating the crystal melting process, absorbing heat, and the temperature remains unchanged.

(3) The material in segment CD is in a liquid state, which means that the liquid absorbs heat and heats up.

(4) Point B means that the material has reached the melting temperature, but has not started to melt, and the material is completely in a solid state; point C means that the crystal has just completely melted, and the material is in a liquid state.

Amorphous melting characteristics:

Continue to absorb heat and the temperature continues to rise.

Understand the crystal melting curve:

It means that amorphous crystals do not have a fixed melting temperature. The whole process attracts heat and the temperature continues to rise.

Rosin, asphalt, glass, etc. in nature are all amorphous.

Let me think about it

Now a certain substance starts to melt at 25 ℃, but does not melt completely until 75 ℃. I would like to ask: Is this substance crystalline or amorphous?

It’s amorphous crystal! Because the substance does not have a fixed melting temperature (melting point).

During the review class, the teacher wrote a couplet. The first couplet is "Ice water in the cup, the water freezes and the temperature does not drop"; the second couplet is "The water in the dish is ice, but the temperature of the frozen water does not rise". The material changes contained in the couplet are ______ and ______, reflecting a commonality which is ______.

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For more information about the "Melting and Solidification Changes in State of Matter" PPT courseware, please click the Melting and Solidification ppt Changes in State of Matter ppt tag.

"Melting and Solidification" PPT courseware:

Contents of the first part of the PPT courseware "Melt and Solidify": Three states of matter: Take water as an example: ice rain, white gas, fog, dew, frost, snow, hail Water vapor Solid state: ice, frost, snow and hail Liquid state: rain, fog, dew, white gas Gaseous state: water Vapor (invisible to the human eye) ... ...

"Melting and Solidification" PPT:

"Melt and Solidification" PPT Part 1 Content: State Changes Solid, liquid, and gaseous states are the three common states of matter. Solid state: such as aluminum, gold, silver, copper, iron, etc. are usually solid. Liquid state: such as water, vinegar, oil, etc. are usually liquid. Gaseous state: such as oxygen, hydrogen,...

"Exploring the Characteristics of Melting and Solidification" Material Forms and Their Changes PPT Courseware 2:

"Exploring the Characteristics of Melting and Solidification" Material Form and Its Changes PPT Courseware 2 Learning Objectives 1. Know what melting and solidification are. Understand the endotherms of melting and the exotherms of solidification. Know the characteristics of crystalline and amorphous melting and solidification. Understand the physical meaning of melting curves. 2. know..

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Update Time: 2024-08-30

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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